1. Field
The following description relates generally to wireless communications, and more particularly to reselecting cells for communicating in wireless networks.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), evolution data optimized (EV-DO), etc.
Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
Moreover, for example, a wireless network can include multiple types of base stations that implement different coverage cells. For example, a base station can provide macrocell coverage, closed subscriber group (CSG) or other femtocell coverage in heterogeneous deployments, and/or the like. In one deployment of a wireless network, macrocells and CSG cells are deployed on a high priority frequency, such that co-channel interference is possible, and the macrocell can have one or more co-located deployments at lower priority frequencies. In addition, devices can perform cell reselection among one or more cells of one or more base stations to maintain connection to a wireless network where communications properties in a current cell become undesirable. In one example, the device can perform a narrowband measurement over the center of the system bandwidth (e.g., over the center six resource blocks, or about 1.08 megahertz) utilized by one or more cells to determine a reference signal received power (RSRP) for discerning whether to perform reselection to one or more other cells.
Where a CSG cell that does not allow communications from the device interferes with the current cell, however, measuring RSRP does not consider such interference, and thus the device continues to communicate with the current cell though the downlink channel quality is inhibited by the CSG cell. In this regard, for example, the RSRP of a current cell can be compared to that of the CSG cell, and if they differ by at least a threshold level, the device can evaluate other frequencies for reselection. In another example, signal-to-interference-and-noise ratio (SINR) or reference signal received quality (RSRQ) can be measured, or otherwise computed, and used to determine whether to perform reselection and/or whether to evaluate other frequencies as well. In one deployment, however, base stations can be offset from the center frequency of the system bandwidth such that partial co-channel interference is possible. Measuring the RSRQ in the narrowband center of the system bandwidth, for example, may not include the interference, and thus may result in RSRQ above the threshold level for evaluating other frequencies (e.g., where the partial co-channel interference exists outside of the narrowband).